-
Bone is?
- HARD
- -highly specialized CT
- -has cells and ECM, just like any other CT
-
Bone has what type of collagen fiber bundles?
Type 1
-
GAGS are?/
hyaluronic acids, chondroitin 4-SO4, keratan SO4
-
Bone also has?
- -INORGANIC COMPOUNDS
- -Ca & PO4 in the form of HYDROXAPATITE CRYSTALS
-
Collagen fibers and inorganic materials make bone extremely?
strong
-
Bone is?
- -relatively light weight
- -somewhat resilient
-
-
What is osteonectin?
structural proteins that bind things together
-
What are the structural things that bind things together in cartilage?
chondronectin
-
What are the structural proteins that bind things together in CT?
fibronectin
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Enamel is __% inorganic & ___% organic & water.
-
Dentin is ___% inorganic, ___% organic, & ___% water.
-
Bone and Cementum are __%inorganic & __% organic+water
-
The %percentage of inorganic material gets less and less as it gets closer to the pulp.
True
-
Because of mineral deposition, bones become ?
- -calcified
- -can bear more weight
- -form rigid skeleton
- -for muscle attachments
-
Cartilage is?
- -semirigid
- -highly hydrated
- -higher water content
- -much more flexible than bone
-
In x-ray. what tooth is the most white?
-What tooth tis the most gray?
- white= enamel
- gray= pulp (soft)
-
For an XRAY ID:
dentin=
enamel=
pulp=
- dentin= gray HARD TISSUE
- enamel= white on top
- pulp= most gray SOFT TISSUE
-
Functions of BONE:
- -enables SKELETON to maintain the body shape
- -for PROTECTION, cranium protects the brain, thoracic cage protects the heart, lungs...
- -serve as LEVERAGE for muscle action, mobility
- -act as RESERVOIR for ions, especially Ca, released from bone when too low in blood & vice versa
- -has BONE MARROW for formation of blood cells
-
Problems occurs because bone is hard:
- -impossible for diffusion of nutrients/wastes
- -impossible to grow interstitially from within
- -impossible to cut section, demineralized first teeth also
- -miss important parts in DEMINERALIZED OR DECALCIFIED SECTION
-
Problems occur because bone is hard: ( continued)
-miss cells/other organic components in DRY GROUND SECTIONS
-
A long bone:
- -shaft or DIAPHYSIS, compact bone
- -ends or epiphyses
-
Spicules are?
(small pieces) of SPONGY or CANCELLOUS BONE
-
Trabeculae are?
(bigger pieces) of SPONGY or CANCELLOUS BONE
-
Trabeculae is?
where cancerous bone is located
-
Trabeculae and spicules?
-look different but both have the SAME IDENTICAL cells, fibers, and ground substance
-
Periosteum?
covers bone, has 2 layers
-
-
Periosteum and Endosteum?
-both provide blood supply
-
What is the Osteon/Haversian system?
collagen fibers arranged in lamellae/layers concentrically organized around a canal= whole complex
-
Harversian canal?
hole in the middle that contains blood vessels & nerves
-
Where is the OUTER CIRCUMFERENTIAL LAMALLAE located?
just beneath the periosteum outside
-
Where is the INNER CIRCUMFERENTIAL LAMELLAE located?
around the marrow cavity
-
Intersitial lamellae is?
irregular lamellae, bits/pieces left after remodeling
-
Volksmann's canal?
communicates between osteons together and to the peri/endosteum
-
Osteoblasts?
- -lay down Harversian systesms
- -lay down ECM
- -trapped in own matrix
- -become OSTEOCYTES located in lacunae
-
Where are osteocytes found?
in lacunae
-
Short/irrgular bones (mandible/maxillary)?
spongy bone surrounded by compact bone
-
FLAT BONES?
2 plates seperated by dipole
-
PRIMARY, IMMATURE, OR WOVEN BONE is?
the first bone formed in embryo and in fracture repair
-
Primary bone is?
immature
-
Secondary bone is?
mature
-
Secondary bone is also called?
- -mature bone
- -LAMELLAR BONE
-
Dry Bone qualities
- -osteons, lamellae
- -Haversian/Volksmann canals
- -lacunae
- -canalliculi, calcified matrix
NO CELLS, FIBERS, NEUROVASCULAR OR LYMPHATICS
-
3 types of bone cells are?
- 1. osteoblasts
- 2.osteocytes
- 3.osteoclasts
-
Osteoblasts are?
bone forming cells
-
Osteoblasts are derived from?
mesenchymal cells
-
Where are osteoblasts located?
located at the surfaces of bone tissue, once cell layer like simple epithelium
-
Osteoblasts have what type of cytoplasm?
Basophilic cytoplasm, active protein producing cells
-
What do osteoblasts lay down?
lay down organic components (type 1 collagen fiber bundle, GAGS, proteins) of bone matrix first
-
Osteoblasts add what type of components later?
inorganic components
-
What is an OSTEIOD?
bone like, later of newly formed bone but NOT yet mineralized
-
Bone can grow by what type of growth?
by appositional growth ONLY
-adds on the surface not by interstitial growth
-
Once surrounded and trapped in their own matrix, osteoblasts stop forming bone, they become?
osteocytes
-
Osteoblasts have receptors for?
Parathyroid hormone
-when activated, will activate and increase the number of osteoclasts
-
Parathyroid hormone promotes?
bone RESORPTION, more Calcium in the blood
-
What happens in MINERALIZATION in both types of bone formation:
- -decrease in water content
- -increase in inorganic content
- -collagen content stays the same, NO CHANGE
-
Osteocytes are located?
in lacunae between lamellae
-
Only __ osteocyte in each space.
one
-
Cells contact each other via cytoplasmic processes in ____, molecular exchange/communication via _____.
- 1. canaliculi
- 2. gap junctions
-
In osteocytes, how does the bone get blood supply?
via canaliculi
-not by diffusion like cartilage
-
osteocytes look like?
-flat, almond shaped cells
-
Osteocytes activity compared to osteoblasts?
osteocytes are LESS ACTIVE than osteoblasts, never inactive
-
Osteoclasts are still actively involved in?
ECM maintenance
-
Cells get rid of wastes via?
gap junctions between them!
-
Osteoclasts are derived from?
monocytes
-
Osteoclasts are?
cells that break down bone (resorption)
-
Osteoclasts are?
- -large
- -multi nucleated cells with Ruffle border
- -located at Howship's lacunae
-
How do osteoclasts attack bone surfacr or resop bone by?
acid phosphatase enzyme reaction
-
Osteoclasts have receptors for?
calcitonin
-secreted by parafollicular of C cells of thyroid gland, which INHIBITS OSTEOCLAST ACTIVITY AND BONE RESORPTION
-
What is bone remodeling?
continuously being removed/replaced in both young and old bones
-
Sharpeys fibers are?
-Type 1 collagen fiber bundles inserted into the bone
-
Sharpeys fibers are seen as?
periodontal ligaments
-anchoring to the bony tooth socket, or where tendon attached to the bone
-
Collagen fiber bundles in the matrix give bone its?
tensile strength
-
Endosteum is?
made up of all the cells lining the marrow cavity
-osteoprogenitor cells, osteoblasts, osteoclasts
-
A bone spicule is formed by?
intramembranous formation from head/neck mesenchyme
-
Intramembranous ossification is?
direct mineralization of matrix secreted by osteoblasts
-
Intracatilaginous/endochondral ossification is?
by deposition of bone matrix on pre-existing cartilage model
-
In intramembranous ossification and intracartilaginous ossification the first bone tissue is?
primary bone (immature or woven) then replaced by secondary bone (mature or lamellar)
-
In intramembranous ossification trapped cells become?
osteocytes
-
What bones are formed from intramembranous ossification?
-flat bones of skull and irregular bones, maxilla & mandible (except sphenoccipital join & condyles of mandibles)
-
In endochondral/intracartiliaginous ossification it occurs within?
pre-existing catilage model
-
Endochondral ossification is found in the formation of?
long/short ones, the condyles of the mandible, sphenocciptial joint
-
Hyaline cartilage models acts as fetal skeleton, is NOT harden and become bone
-
Bone collar is produced?
at local perichondrium
-
Primary ossification center is?
at the center
-
Secondary ossification centers is at?
both ends
-
Articular cartilage ?
persists thru out adult life, does not contribute to bone growth in length
-
Epiphyseal plate or growth plate is responsible for bone growth in?
length
-disappears in adults, strop growing in height, remnants= epiphyseal lines
-
Step/Zones in endochondral osteogenesis:
- 1. Resting zone
- 2. Zone of proliferation
- 3. Zone of hypertrophy
- 4. Zone of calcification
- 5. Zone of ossification
- 6. Resorption
-
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